<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta charset="UTF-8">
    <title>image</title>
    <script type="text/javascript">
        window.onload=function () {
            document.getElementById("btn1").onclick=function () {
                changesize();}
            document.getElementById("btn2").onclick=function () {
                changeimg();}
        }
        function changesize() {
            document.getElementById("about").height="31";
            document.getElementById("about").width="88";
        }
        function  changeimg() {
            document.getElementById("about").src="../sourcebook/valid-xhtml10.png";
        }
    </script>
</head>
<body>
<img id="about" src="../sourcebook/about.gif" alt=""><br>
<input type="button" id="btn1" value="改变图像大小"><br>
<input type="button" id="btn2" value="更换图像">
</body>
</html>